Jury selection began today in the terrorism trial of a young Somali-American. He's accused of trying to bomb a Christmas tree lighting ceremony in Portland, Oregon two years ago. But the case is drawing attention for another reason: There was no bomb. The defendant was the target of an FBI sting operation.

And as NPR's Dina Temple-Raston reports, his lawyers are expected to argue their client was entrapped.

DINA TEMPLE-RASTON, BYLINE: Mohamed Mohamud was arrested in November 2010, for allegedly trying to detonate a car bomb he'd parked outside a Christmas tree lighting ceremony in downtown Portland. If those were the only facts in the case, Mohamud's trial wouldn't be getting so much attention.

What makes this trial different is that the car bombing plot - the purchase of the car, the gathering of explosives, the plan itself - was orchestrated by the Federal Bureau of Investigation. Mohamud was the target of an FBI sting and his lawyers say he was entrapped.

SAM RASCOFF: Well, there is a certain measure of truth to that.

TEMPLE-RASTON: That's Sam Rascoff. He teaches national security law at New York University. And he says Mohamud's lawyers may have a point.

RASCOFF: It's quite likely that this guy would not have actually gotten to a point where he would have been positioned, in his mind, to blow up the Pioneer Square Christmas tree lighting in Portland, but for the intervention of the Feds.

TEMPLE-RASTON: Legal experts are watching the Mohamud trial so closely because the facts in the case could lend themselves in a unique way to an entrapment defense. Mohamud was only 19 years old when he was arrested, making him one of the youngest people ever to be arrested on terrorism charges. And because of his youth, he could be positioned to convince a jury that he was manipulated by the FBI into committing a crime.

Rascoff says there is a problem with that argument, though. Mohamud actually dialed the cell phone code to detonate what he thought was a bomb.

RASCOFF: Here's someone who was minded to do it. So, yes, the Feds clearly played a role in getting him to the finish line. But he was someone who was predisposed, so it appears, to wanting to do it himself.

TEMPLE-RASTON: That's the FBI's argument. They say Mohamud drew their attention when he started writing articles for jihadi online publications. Prosecutors say Mohamud tried to contact terrorists overseas. He was dangerous, they claim, because he seemed determined to commit some sort of violence in the name of jihad.

Rascoff says being a misguided 19-year-old probably isn't enough to get Mohamud off.

RASCOFF: We all know that teenagers are teenagers and they're prone to doing some rash things every once in a while, but in the eyes of the American criminal law, a 19-year-old is an adult.

TEMPLE-RASTON: Mohamud's lawyers, who are not speaking on the record about the case, have made clear in court documents that part of their defense will be that the FBI confused teenage bravado with terrorism.

The trial also comes at a time when more than a decade after the 911 attacks, there's a growing skepticism about FBI stings. Providing fake explosives and detonating devices strikes many observers as overreach. And that argument could resonate, particularly in Portland. It is considered a liberal community, and some defense attorneys say it is one of the two or three best places to test this kind of defense.

That said, entrapment defenses in terrorism cases haven't worked. Since 2001, there have been entrapment defenses in 11 cases and none of them have succeeded in winning an acquittal.